Sir Karl Popper (1902-1994): in memoriam, 15 years later

September 17th, 2009 marks the 15th anniversary of Sir Karl Popper's death. Popper was an outspoken champion of critical rationalism, and a constant critic of authoritarian tendencies in science and society. He was also one of the spiritual founders of this journal and served on its first editorial advisory board. Popper was recognized around the world as one of the 20th century's greatest philosophers of science and one of its most articulate and influential critics of Marxism and closed society. When he died, the contemporary wisdom among professional philosophers was that his philosophy was generally right-but somehow obsolete. Some commentators said that it was now obvious that scientific theories cannot be shown to be true. Others said that we had witnessed the end of history and that his critique of closed societies, while no doubt important in its day, had been fully assimilated into Western thinking and still had meaning, if at all, only for the democracies in transition that were trying to emerge from the former Soviet Union. But 15 years after his death, a look at science and society around the world gives us good reason to remember his philosophy.